南海断面春季放射虫残骸的空间分布及其与表层沉积记录对比

SPATIAL DISTRIBUTION OF DEAD RADIOLARIANS IN SPRING UPPER WATERS OF THE SOUTH CHINA SEA,AND ITS COMPARISON WITH THE SURFACE SEDIMENT RECORD

放射虫是揭示古海洋环境信息的重要载体。本文采用虎红染色方法,首次揭示了南海典型断面现代放射虫残骸群的空间分布特征,并比较分析现代水体中放射虫残骸群与海底表层沉积物中放射虫化石群的相互关系。结果表明:南海春季放射虫残骸群比较丰富,其丰度一般呈现出随深度增加而增高的趋势,最高值主要出现在75—300m深即位于叶绿素最大值层和活体高峰深度之下;分析发现研究区放射虫残骸丰度的深度分布受到海流的横向输运影响;春季水体和表层沉积物中放射虫属种组成和丰度分布的差异表明,除了现代放射虫具有季节性变化之外,海流的横向传输也是一个很重要的原因。在150—300m水体中除了Cornutella profunda和Cyrtopera laguncula,还发现了Cycladophora davisiana的残骸,推测典型冷水种C.davisiana由于受到径向翻转流的作用,从中深层水被带到了中上层水体中。

Polycystine radiolarians are one of the important tools to be used widely for paleoceanographic and paleoen- vironmental reconstruction. By staining plankton samples with Rose-bengal, we disclosed firstly the spatial distribu- tion of dead radiolarian in the typical sections of the South China Sea （SCS） in spring, and analyzed the relationship between dead radiolarians in upper waters and those in the surface sediments. The results showed that the dead radio- larians in spring of the SCS are relative abundant, increasing with water depth, and the highest abundance generally occur at depths of 75-300 m, i. e , below the chlorophyll-a maximum and the highest density of living radiolarians. The depth-distribution of dead radiolarian abundance was affected by the lateral advection of ocean current; the differ- ence on species composition and abundance distributions between the upper waters in spring and the surface sediments was due to the seasonal variance of modern radiolarians and the lateral advection of ocean current. Interestingly, in addition to Cornutella profunda and Cyrtopera laguncula, Cycladophora davisiana was found at the depth of 150-- 300 m, in which the typical cold species C. davisiana could be brought to the upper-middle layer waters from the low- er-middle layer waters by the meridional overturning circulation.